Heat exchanger



March 21, 1933. L. P. WHITAKER HEAT EXCHANGER Original Filed Jan. 31,1931 2 Sheets-Sheet INVENTOR Patented Mar. 21, 1933 UNITED STATES PATENTOFFICE LOUIS PREVOST WHITAKER, OF NEW YORK, N. Y., ASSIGNOR TO S. R.DRESSER MANU- FACTURING COMPANY, OF BRADFORD, PENNSYLVANIA, ACORPORATION OF PENN- SYLVANIA HEAT EXCHANGEB My invention consists inthe novel features hereinafter described, reference being had to theaccompanying drawings which show one embodiment of my invention,selected by me for purposes of illustration, and the said invention isfully disclosed in the following description and claims.

My invention relates to heat exchangers adapted especially for thetransmission of heat, in heating oricooling systems. The process bywhich my improved heat exchangers are preferably manufactured ashereinafter described, forms no part of my present invention and is notclaimed herein, as it forms the subject matter of myformer applicationfor Letters Patent of the United States filed January 31, 1931, SerialNo. 512,577, of which this application is a divi- 5101].

Heat exchangers of this kind ordinarily comprise a plurality offins orplates in' spaced parallel relation and extending in ;all directionsfrom a fluid conducting passage or conduit with which the fins areunited. It has been proposed heretofore to form a heat exchanger of thiskind by employing a plurality of apertured plates provided with spacingelements, usually integral with the plates, and in the form of acylindrical flange coaxial with the central aperture therein, theflanges of said plates being placed upon a heavy supporting pipe whichforms the conducting passage, and the plates and supporting galvanizing,soldering, brazing or welding the flanges of the plates to thesupporting pipe. This construction presents a number of disadvantages,one of which is the difficulty in securing and maintaining asatisfactory union between the supporting pipe and the plates, to insurerapid conductivity of heat from the interior of the pipe to the fins, orvice versa, and the production of such heat exchangers 0r fin units isvery expensive. particularly where the plate flanges are welded orbrazed to the pipe. I am also aware of the fact that it has beenproposed to assemble in a built up structure a plurality of aperturedplates or fins with alternating spacing members between them, provid-'-sembled tube and P p being united by Divided. and this applicationfiled October Serial No. 568,008.

ing a removable internal core of less external diameter than theinternal diameter of the longitudinal space formed within said aperturedplates, and spacing members, and casting a cylindrical body between saidcore and he spacing members in such manner that portions of the plateswill be anchored or embedded in the casting, for the purpose of unitingthe plates with the cast portion, which provides the fluid conductingpassage of the unit and becomes the supporting member thereof. I

According to my present'invention in its preferred form I employ aplurality of apertured plates provided with spacing members coaxial withthe apertures therein, and formed conveniently integrally with theplates. These plates are arranged in a built up structure, withcylinder, which is preferably formed of metal of high heat conductingcapacity, the spacing members of the plates being spaced annularly fromthe interior tube coaxial relation therewith. The spacing members areconveniently provided with inwardly extending separated lugs orprojections engaging the interior tube at separated points, while thespace between the tube and the spacing members of all of the plates ofthe series is in direct communication throughout the length of the unit.The as- 7 plates are preferably clamped in assembled relation. andsupported in a vertical position upon a suitable supand maintained inend of the annular space between the interior tube and the spacingelements of the plates, and cast metal ispoured into this annular spaceso as to rigidly and permanently unite the plates and also the innertube, which forms the inner mold wall, while the outer mold wall isformed by the spacing members. Wherethe spacing members are providedwith centering lugs to engage and center the inner tube, such lugs wouldbe anchored or embedded in the cast metal. The built up structure ispreferably heated before or during the casting operation to facilitatethe flow of the metal. I prefer to introduce a .end of the inner tube,so as to facilitate the casting operation.

By forming the heat exchanger or fin heating unit in this manner, acomparatively thin body of cast metal may be formed which reinforces thelight inner tube and unites it and the plates or fins into asubstantiallyintegral structure, which readily transmits heat from theinterior of-the inner tube to the fins, or vice versa. Suitableinternally threaded. collars are preferably inserted in 'theoppositeends of the thin inner tube, by

pressing them into the'same, or otherwise securing them thereto, eitherbefore or after the casting operation, but preferably before the castmetal is poured, which collars facilitate the connection of pipefittings of usual character to the unit. A plain end plate, or plates,may be applied to the built up structure and secured in any desiredmanner thereto, or to the screw collars, to give a desired finish to theunit. V

My invention also comprises the novel features of construction andcombination of parts hereinafter fully described and partieularlypointed out in the claims.

Referring to theaccompanying drawings,

Fig. 1 is a sectional view, with the central portion omitted, andindicated by dotted lines, showing a plurality of plates or finsassembled upon an interior thin walled tubular member and supported inposition for casting the annular connecting body between said tubularmember and the spacing mem-- bers of the plates.

Fig. 2 is a top plan view of one of said plates.

Fig. 3 is a perspective view, partly in section, of a portion of two ofthe'plates in as- I sembled relation.

Fig. 4 isa side view, partly in section and partly broken away, of acompleted heat exchanger or fin heating unit.

Fig. 5 is a top plan View of a modified form of plate.

Fig. '6 represents a section on the line 66 of Fig. 5.

In carrying out my invention, I form plurality of plates or fins,indicated at l, which are preferably pressed or stamped from sheetmetal. such as copper, aluminum, iron or steel, for example. The platesmay be circular or rectangular or of any other desired form. Each plateis provided with 'stitute the outer mold wall.

an aperture, indicated at la, although it will be understood that eachplate may have more than one aperture if the plates are to be providedwith a plurality of tubular passages. As shown, the aperture, 1a, iscentrally located, and the plate, 1, is provided with an annularsubstantially cylindrical fiange,,2, surrounding the aperture, 1a, andcoaxial therewith. These annular flanges form integral spacing membersfor spacing the plates longitudinally 'with respect to the tubularpassage, and I prefer to provide said spacing members at their freeedges with inwardly extending separated lugs, 3, 3, three of which areindicated in the drawings, see Fig. 21, and which serve the function ofcentering the plates with respect to the inner tube. These lugs,however, may be omitted and the tube may be centered in other ways. Eachlate is also preferably provided with auxl lary spacing elements,

indicated at 4, which may be conveniently formed by struck-up portionsof the metal of the plate extending at right angles thereto and of aproper length to serve as the spacing elements, in the manner indicatedin the drawings. The plates, 1, are also provided,preferably withaplurality of bolt holes, 5, the bolt holes of the several plates beingin alignment when the plates are assembled, so that the plates may betemporarily united by suitable bolts, one of which is indicated at 6 inFig. .1, for example. 7 represents a tubular member of cylindrical orother preferred form corresponding with the form of the apertures in theplates and being sufficiently smaller in cross section than saidapertures, so as to form a space, indicated at 8, betweenthe inner faceof the spacing members, 2, of the assembled plates, and the outersurface of the tube.

I find it convenient to assemble the desired number of plates to form aunit of desired length, in the manner illustrated in Fig. 1, upon aremovable base plate, indicated at 9, which is provided with a centralaperture, 10, conforming to-the exterior surface of'the tube 7, andhaving an annular recess, 11, to accommodate the spacing member, 2, ofthe lowermost plate of the series, the bottom of said recess forming ineffect the bottom of the mold of which the thin tubular member, 7, isthe inner mold wall, and the spacing elements of the plates con- Thespacing elements, 2, when formed integrally with the plates may be madeof slightly smaller diameter at the ends remote from the body of theplate. so as to enter to a greater or less extent, as desired, the upperportion of the next adjacent spacing member, thus enabling the plates tobe nested to a certain extent. This arrangement will assist inpreventing any leakage of the molten metal. but it is not essential, andthe spacing mem- Ill bers, 2, may be of uniform diameter throughout andhave their lower ends abut directly against the main body of the adjacent plate, so as to bring the spacing members into direct alignment,if desired. The

' before the casting operation.

bottom supporting plate, 9, will also be provided with recesses orpockets, 12, to accommodate the auxiliary spacing elements, 4, of thelowest plate of the series, if desired, and will also be provided withmeans,as threaded apertures, 5, one of which is shown in Fig. 1, forengaging threaded portions, 15a, of the bolts, 6, which clamp the platesin assembled relation. I prefer to provide the thin tubular member, 7,at each end with an internally threaded collar indicated at 13, whichmay be and preferably is pressed therein or otherwise connectedtherewith. It will be understood that the built up structure illustratedin Fig. 1, may be assembled in quantity and may be readily transportedfrom the place of assembly to the place where the casting operation isto be performed.

The central tubular member forming the inner mold wall is held incentered position in the apertures of the plates by the inwardlyextending lugs, 3, if they are provided. It will-be understood, however,that the plates alone may be built up, secured together in the mannerdescribed, and transported to the place where the casting operation isto be performed, and that the central tubular member, 7, may be insertedjust It will also be understood that the tubular member may be held incentered relation to the plate apertures by the aperture, 10, at thebottom of the supporting plate, 9, and by any suitable means engagingthe upper end of the tubular member, and held in fixed relation with theplates, if it is desired to omit the lugs, 3.

I prefer to heat the built up structure preparatory to or during thecasting operation. Obviously this can be done by passing the built upstructures through a heating chamber on a suitable conveyor, on theirway to the point of casting. I find it convenient, however, to provide aheating burner, 14, or burners, below the lower end of the tubularmember, which presents an uninterrupted passage for a heating mediumsuch as the products of combustion from said burner, the heating mediumpassing from the bottom upwardly, while the cast metal will flow fromthe upper part of the built up structure downwardly, thus preventing thecasting metal from cooling too rapidly, and insuring the formation ofsubstantially uniform castings. The cast metal, which is preferably ametal or alloy having a lower melting point than the metal forming theinner tubular member and the spacing elements, is poured into theannular space between the inner and outer mold walls, and upon coolingforms a substantially' cylindrical cast metal body,which is firmly.united to both the inner tubular member, 7, and the spacing members ofthe plates, the centering lugs, 3, of the plates, if they are employed,being firmly anchored and embedded in the bodyof the cast metal. Iprefer, as before stated, to apply the heating medium to the interior ofthe tubular member, 7, during the pouring of the. cast metal, tofacilitate the casting operation, and'in this'way acomparatively thincast metal body or wall may be formed, it being only necessary that thiscast' metal wall, as reinforced by the inner tubular member, 7, and thespacing members, shall have sulficient strength to support the unit. Iam thus able to obtain the necessary strength for the tubular member ofthe unit, with a comparatively thin body of cast metal, rigidly unitingthe inner tube and the plates and their spacing elements into anintegral structure; In this way the unit can not only be made lighterthan would be the case where the thick cast wall is formed which alonemust provide practically 'all the strength required for the tubularmember of the unit, but the thinning of the cast wall greatlyfacilitates the exchange of heat between the tubular member and theplates and fins. Furthermore, the inner tube element, which ispreferably made of copper or other metal having high heat conductingproperties, can be made very thin, comparatively, as it is not requiredto furnish the strength for the tubular member, this also increasing theconductivity of the unit and keeping down the cost of the same.

The bond between the cast metal and the tubular member, plates andspacing members, will depend upon the character of the metals employed.For example, the bond may be formed by the shrinkage of the metal incooling, in which case'the surfaces will be held in mechanical contactin a man ner similar to mechanical clamping. On the other hand, theremay be a direct adhesion between the cast metal and the contactingportions of the tube, and plates, analogous to brazing or soldering, andin some instances, as where the cast metal is of the same or nearly thesame type, as the metal from which the plates are made, and projectingportions of the plates or the spacing elements thereof, project into thecast metal, there may even be fusion, that is to say union analogous towelding between the cast metal and portions of the plates or spacingmembers. In such cases, however, it may be desirable or necessary tosupport the inner and outer mold walls, as by embedding them I in sand,for example, or otherwise to previded each with a single tubularconducting passage, units may be formed in like manner with two or moretubular passages, if

desired. I prefer, however, to form them as shown, as it enables the useof plates of comparatively small dimensions, which permits them to bestamped, pressed or formed from scrap plate or other waste material withcorresponding economy of production.

For the cast metal body I may employ aluminum or an alloy of the same orany other desired fusible metal having the necessary characteristics toenable it to be poured between the tube, and the exterior mold wallformed by the plates and their spacing elements, and uniting the tube,cast metal body and plates and spacing elements, into a substantiallyintegral body. Fig. 4 shows one of the completed units, the tube memberbeing shown provided at each end with the internally threaded collars,13, for the attachment of pipe connections, but it is to be understoodthat the connectin pipes may be attached in any other desire manner. Thecast metal body, which unites the tube member and plate and spacingmembers therewith, to form the integral structure, is indicated at 16,the inwardly projecting portions, 3, of the spacing elements being shownembedded in the cast metal body. In some instances, if desired, plainapertured finishing plates or end plates, indicated at 17, may beprovided at each end of the unit and secured to the unitary structure,by being pressed over projecting portions of the tube, 7, or of thecollars, 13, or they may be held in position in any other desiredmanner.

In Figs. 5 and 6, in which the corresponding parts are given the samereference numerals with the addition of 100, I have illustrated amodified form of plate, 101, which in this instance is rectangular inform, provided with a central aperture, 101a, and annular spacingelement, 102, surrounding the same, two parallel edges of each platebeing bent angularly on the same side of the plate as the spacingelement, 102, to form lateral flanges, 104, constituting the auxiliaryspacing elements, and the marginal edges of the spacing elements, 102,are also shown as provided with the inwardly extending centeringprojections, 103, to engage and center the tube element in the built upstructure. The plate, 101, is also shown provided with two oppositelydisposed bolt holes, 105, to receive the clamping bolts for clamping theplates in assembled relation in the manner indicated in Fig. 1.

\Vhile I have shown a heating burner for heating the interior of thetube element, any other suitable heating means may be employed.

What I claim and desire to secure byLetters Patent is:

ing the only connection between said plates and said tube.

2. A heat exchanger comprising a thin 'metal tube, a plurality ofparallel plates surrounding the same and provided with spacing elementslocated between said plates and surrounding said tube, and an integralcylindrical reinforcing cast metal body be tween said tube and saidspacing elements, connecting said tube, plates and the spacing elements,therewith, to form an integral structure.

3. A heat exchanger comprising a thin tube, a plurality of aperturedplates provided with integral spacing elements surrounding the aperturestherein, and an integral cylindrical reinforcing cast metal body locatedbetween said tube and said spacing elements, and uniting the tube,plates and spacing elements therewith, to

orm an integral structure.

4. A heat exchanger comprising a thin metal tube, a plurality ofapertured plates surrounding said tube, and provided with' integralspacing elements surrounding the tube and having inwardly extendingseparated projections engaging the tube, and an integral cylindricalreinforcing cast metal body located between the spacing elements and thetube, and having said separated projections of the plates embeddedtherein, and unitingthe tube, spacing elements and plates therewith, toform a unitary structure.

5. A heat exchanger comprising a thin metal tube, a plurality of spacedparallel plates disposed perpendicularly to the axis of said tube andextending outwardly therefrom, and an integral cylindrical reinforcingcast metal body interposed between the outer surface of said tube andthe inner edge portions of said plates, united to said tube and to saidplates and forming a unitary structure, said cast metal body forming theontly connection between said plates and said tu e.

6. A heat exchanger comprising a thin metal tube, a plurality ofparallel plates disposed perpendicularly to the axis of said tube andextending outwardly therefrom, and plates having separated inwardlyextending centering projections engaging said tube, and an integralcylindrical reinforcing cast metal body between the outer surface ofsaid tube and the inner edge portions of said plates, united to saidtube and plates and enclosing said centering projections and forming aunitary structure.

7. A heat exchanger comprising a thin metal tube, a series of. parallelplates of sheet metal having apertures substantially surrounding saidtube but of greater diam- LOUIS PREVOST WHITAKER.

